Mobile Sensing Systems

[EN] Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high.This work has been partially supported by the "Ministerio de Ciencia e Innovacion", through the "Plan Nacional de I+D+i 2008-2011" in the "Subprograma de Proyectos de Investigacion Fundamental", project TEC2011-27516, and by the Polytechnic University of Valencia, through the PAID-05-12 multidisciplinary projects.Macias Lopez, EM.; Suarez Sarmiento, A.; Lloret, J. (2013). Mobile Sensing Systems. Sensors. 13(12):17292-17321. https://doi.org/10.3390/s131217292S1729217321131

A Longitudinal View at the Adoption of Multipath TCP

Multipath TCP (MPTCP) extends traditional TCP to enable simultaneous use ofmultiple connection endpoints at the source and destination. MPTCP has beenunder active development since its standardization in 2013, and more recentlyin February 2020, MPTCP was upstreamed to the Linux kernel. In this paper, weprovide an in-depth analysis of MPTCPv0 in the Internet and the first analysisof MPTCPv1 to date. We probe the entire IPv4 address space and an IPv6 hitlistto detect MPTCP-enabled systems operational on port 80 and 443. Our scansreveal a steady increase in MPTCPv0-capable IPs, reaching 13k+ on IPv4(2$\times$ increase in one year) and 1k on IPv6 (40$\times$ increase). MPTCPv1deployment is comparatively low with $\approx$100 supporting hosts in IPv4 andIPv6, most of which belong to Apple. We also discover a substantial share ofseemingly MPTCP-capable hosts, an artifact of middleboxes mirroring TCPoptions. We conduct targeted HTTP(S) measurements towards select hosts and findthat middleboxes can aggressively impact the perceived quality of applicationsutilizing MPTCP. Finally, we analyze two complementary traffic traces fromCAIDA and MAWI to shed light on the real-world usage of MPTCP. We find thatwhile MPTCP usage has increased by a factor of 20 over the past few years, itstraffic share is still quite low.<br

Performance Assessment of Aggregation and Deaggregation Algorithms in Vehicular Delay-Tolerant Networks

Vehicular Delay-Tolerant Networks (VDTNs) are a new approach for vehicular communications where vehicles cooperate with each other, acting as the communication infrastructure, to provide low-cost asynchronous opportunistic communications. These communication technologies assume variable delays and bandwidth constraints characterized by a non-transmission control protocol/ internet protocol architecture but interacting with it at the edge of the network. VDTNs are based on the principle of asynchronous communications, bundleoriented communication from the DTN architecture, employing a store-carryand- forward routing paradigm. In this sense, VDTNs should use the tight network resources optimizing each opportunistic contact among nodes. At the ingress edge nodes, incoming IP Packets (datagrams) are assembled into large data packets, called bundles. The bundle aggregation process plays an important role on the performance of VDTN applications. Then, this paper presents three aggregation algorithms based on time, bundle size, and a hybrid solution with combination of both. Furthermore, the following four aggregation schemes with quality of service (QoS) support are proposed: 1) single-class bundle with N = M, 2) composite-class bundle with N = M, 3) single-class bundle with N > M, and 4) composite-class bundle with N > M, where N is the number of classes of incoming packets and M is the number of priorities supported by the VDTN core network. The proposed mechanisms were evaluated through a laboratory testbed, called VDTN@Lab. The adaptive hybrid approach and the composite-class schemes present the best performance for different types of traffic load and best priorities distribution, respectively

A Lightweight Attribute-Based Access Control System for IoT.

The evolution of the Internet of things (IoT) has made a significant impact on our daily and professional life. Home and office automation are now even easier with the implementation of IoT. Multiple sensors are connected to monitor the production line, or to control an unmanned environment is now a reality. Sensors are now smart enough to sense an environment and also communicate over the Internet. That is why, implementing an IoT system within the production line, hospitals, office space, or at home could be beneficial as a human can interact over the Internet at any time to know the environment. 61% of International Data Corporation (IDC) surveyed organizations are actively pursuing IoT initiatives, and 6.8% of the average IT budgets is also being allocated to IoT initiatives. However, the security risks are still unknown, and 34% of respondents pointed out that data safety is their primary concern [1]. IoT sensors are being open to the users with portable/mobile devices. These mobile devices have enough computational power and make it di cult to track down who is using the data or resources. That is why this research focuses on proposing a dynamic access control system for portable devices in IoT environment. The proposed architecture evaluates user context information from mobile devices and calculates trust value by matching with de ned policies to mitigate IoT risks. The cloud application acts as a trust module or gatekeeper that provides the authorization access to READ, WRITE, and control the IoT sensor. The goal of this thesis is to offer an access control system that is dynamic, flexible, and lightweight. This proposed access control architecture can secure IoT sensors as well as protect sensor data. A prototype of the working model of the cloud, mobile application, and sensors is developed to prove the concept and evaluated against automated generated web requests to measure the response time and performance overhead. The results show that the proposed system requires less interaction time than the state-of-the-art methods

Smartphone traffic characteristics and context dependencies

Smartphone traffic contributes a considerable amount to Internet traffic. The increasing popularity of smartphones in recent reports suggests that smartphone traffic has been growing 10 times faster than traffic generated from fixed networks. However, little is known about the characteristics of smartphone traffic. A few recent studies have analyzed smartphone traffic and given some insight into its characteristics. However, many questions remain inadequately answered. This thesis analyzes traffic characteristics and explores some important issues related to smartphone traffic. An application on the Android platform was developed to capture network traffic. A user study was then conducted where 39 participants were given HTC Magic phones with data collection applications installed for 37 days. The collected data was analyzed to understand the workload characteristics of smartphone traffic and study the relationship between participant contexts and smartphone usage. The collected dataset suggests that even in a small group of participants a variety of very different smartphone usage patterns occur. Participants accessed different types of Internet content at different times and under different circumstances. Differences between the usage of Wi-Fi and cellular networks for individual participants are observed. Download-intensive activities occurred more frequently over Wi-Fi networks. Dependencies between smartphone usage and context (where they are, who they are with, at what time, and over which physical interface) are investigated in this work. Strong location dependencies on an aggregate and individual user level are found. Potential relationships between times of the day and access patterns are investigated. A time-of-day dependent access pattern is observed for some participants. Potential relationships between movement and proximity to other users and smartphone usage are also investigated. The collected data suggests that moving participants used map applications more. Participants generated more traffic and primarily downloaded apps when they were alone. The analyses performed in this thesis improve basic understanding and knowledge of smartphone use in different scenarios

Towards assessing information privacy in microblogging online social networks. The IPAM framework

Les xarxes socials en línia incorporen diferents formes de comunicació interactiva com serveis de microblogs, compartició de fitxers multimèdia o xarxes de contactes professionals. En els últims anys han augmentat els escàndols públics en relació amb pràctiques qüestionables de la indústria de les xarxes socials pel que fa a la privacitat. Així, doncs, cal una avaluació efectiva i eficient del nivell de privacitat en les xarxes socials en línia. El focus de la present tesi és la construcció d'un esquema (IPAM) per a identificar i avaluar el nivell de privacitat proporcionat per les xarxes socials en línia, en particular per als serveis de microblogs. L'objectiu d'IPAM és ajudar els usuaris a identificar els riscos relacionats amb les seves dades. L'esquema també permet comparar el nivell de protecció de la privacitat entre diferents sistemes analitzats, de manera que pugui ser també utilitzat per proveïdors de servei i desenvolupadors per a provar i avaluar els seus sistemes i si les tècniques de privacitat usades són eficaces i suficients.Las redes sociales en línea incorporan diferentes formas de comunicación interactiva como servicios de microblogueo, compartición de ficheros multimedia o redes de contactos profesionales. En los últimos años han aumentado los escándalos públicos relacionados con prácticas cuestionables de la industria de las redes sociales en relación con la privacidad. Así pues, es necesaria una evaluación efectiva y eficiente del nivel de privacidad en las redes sociales en línea. El foco de la presente tesis es la construcción de un esquema (IPAM) para identificar y evaluar el nivel de privacidad proporcionado por las redes sociales en línea, en particular para los servicios de microblogueo. El objetivo de IPAM es ayudar a los usuarios a identificar los riesgos relacionados con sus datos. El esquema también permite comparar el nivel de protección de la privacidad entre diferentes sistemas analizados, de modo que pueda ser también utilizado por proveedores de servicio y desarrolladores para probar y evaluar sus sistemas y si las técnicas de privacidad usadas son eficaces y suficientes.Online social networks (OSNs) incorporate different forms of interactive communication, including microblogging services, multimedia sharing and business networking, among others. In recent years there has been an increase in the number of privacy-related public scandals involving questionable data handling practices in OSNs. This situation calls for an effective and efficient evaluation of the privacy level provided by such services. In this thesis, we take initial steps towards developing an information privacy assessment framework (IPAM framework) to compute privacy scores for online social networks in general, and microblogging OSNs in particular. The aim of the proposed framework is to help users identify personal data-related risks and how their privacy is protected when using one OSN or another. The IPAM framework also allows for a comparison between different systems' privacy protection level. This gives system providers, not only an idea of how they are positioned in the market vis-à-vis their competitors, but also recommendations on how to enhance their services

Measurements and analysis of online social networks

Mención InternacionalOnline Social Networks (OSNs) have become the most used Internet applications attracting hundreds of millions active users every day. The large amount of valuable information in OSNs (not even before available) has attracted the research community to design sophisticated techniques to collect, process, interpret and apply these data into a large range of disciplines including Sociology, Marketing, Computer Science, etc. This thesis presents a series of contributions into this incipient area. First, we present a comprehensive framework to perform large scale measurements in OSNs. To this end, the tools and strategies followed to capture representative datasets are described. Furthermore, we present the lessons learned during the crawling process in order to help the reader in a future measurement campaign. Second, using the previous datasets, this thesis address two fundamental aspects that are critical in order to have a clear understanding of the Social Media ecosystem. One the one hand, we characterize the birth and grow of OSNs. In particular, we perform a deep study for a second generation OSN such as Google+ (a OSN released by Google in 2011) and compare its growth with other first generation OSNs such as Twitter. On the other hand, we characterize the information propagation in OSNs in several manners. First, we use Twitter to perform a geographical analysis of the information propagation. Furthermore, we carefully analyze the propagation information in Google+. In particular, we analyze the information propagation trees and the information propagation forests that analyze the propagation information of a piece of content through multiple trees. To the best of our knowledge any previous study has addressed this issue. Finally, the last contribution of this thesis focuses on the analysis of the load received by an OSN system such as Twitter. The conducted research lead to the following main four findings: (i) Second Generation OSNs are expected to grow much faster that the correspondent First Generation OSNs, however they struggle to get users actively engage in the system. This is the case of G+ that is growing at a impressive rate of 350K new users registered per day. However a large fraction (83%) of its users have never been active, and those that present activity are typically significantly less engaged in the system than users in Facebook or Twitter. (ii) The information propagates faster but following shorter paths in Twitter than in G+. This is a consequence of the way in which information is shown in each system. Secuentialbased systems such as Twitter force short-term conversations among their users whereas Selective-based systems such as those used in G+ or Facebook chooses which content to show to each user based on his preferences, volume of interactions with other users, etc. This helps to prolong the lifespan of conversations in the OSN.(iii) Our analysis of the geographical propagation of information in Twitter reveals that users tend to send tweets from a sole geographical location. Furthermore, the level of locality associated to the social relationships varies across countries and thus for some countries like Brazil it is more likely that the information remains local than for other countries such as Australia. (iv) Our analysis of the load of Twitter system indicates that the arrival process of tweets follows a model similar to a Gaussian with a noticeable day-night pattern. In short the work presented in this thesis allows advancing our knowledge of the Social Media ecosystem in essential directions such as the formation and growth of OSNs or the propagation of information in these systems. The important reported findings will help to develop new services on top of OSNs.Las redes sociales (OSNs por sus siglas en inglés) se han convertido en una de las aplicaciones más usadas de Internet atrayendo cientos de millones de usuarios cada día. La gran cantidad de información valiosa en las redes sociales (que antes no estaba disponible) ha llevado a la comunidad cientifica a diseñar sofisticadas tecnicas para recoger, procesar, interpretar y usar esos datos en diferentes disciplinas incluyendo sociología, marketing, informática, etc. Esta tesis presenta una serie de contribuciones en esta incipiente área. Primero, presentamos un completo marco que permite realizar medidas a gran escala de redes sociales. Con este propósito, el documento describe las herramientas y estrategias seguidas para obtener un conjunto de datos representativo. Tambien, añadimos las lecciones aprendidas durante el proceso de obtención de datos. Estas lecciones pueden ayudar al lector en una futura campaña de medidas sobre redes sociales. Segundo, usando el conjunto de datos obtenido con las herramientas descritas, esta tesis aborda dos aspectos fundamentales que son críticos para entender el ecosistema de las redes sociales. Por un lado, caracterizamos el nacimiento y crecimiento de redes sociales. En particular, llevamos a cabo un análisis en profundidad de una red social de segunda generación como Google+ (una red social lanzada por Google en 2011) y comparamos su crecimiento con otras redes sociales de primera generación como Twitter. Por otro lado caracterizamos la propagación de la información en redes sociales de diferentes maneras. Primero, usamos Twitter para llevar a cabo un analisis geográfico de la propagación de la información. También analizamos la propagación de la información en Google+. En particular, analizamos los árboles de propagación de información y los bosques de propagación de información que incluyen la información sobre la propagación de una misma pieza de contenido a traves de diferentes árboles. A nuestro saber, este es el primer estudio que aborda esta cuestión. Por último, analizamos la carga soportada por una red social como Twitter. La investigación realizada nos lleva a los siguientes 4 resultados principales: (i) Es de esperar que las redes sociales de segunda generación crezcan mucho más rápido que las correspondientes de primera generaci´on, sin embargo, estas tiene muchas dificultades para mantener los usuarios involucrados en el sistema. Este es el caso de G+ que está creciendo al impresionante ritmo de 350K nuevos usuarios registrados por dia. Sin embargo una gran fracción (83%) de ellos no ha llegado nunca a ser activos y los que presentan actividad presentan en general una actividad menos que los usuarios de Facebook o Twitter. (ii) La información se propaga más rápido pero siguiendo caminos más cortos en Twitter que en G+. Esto es una consecuencia de la manera en la que la información es mostrada en cada sistema: sistema secuenciales como en Twitter fuerzan que la información sea consumida al instante mientras que sistemas selectivos como el usado en G+ o Facebook, donde la información que se muestra depende las preferencias de los usuarios y el volumen de interacción con otros usuarios ayuda a prolongar la vida del contenido en la red social. (iii) Nuestro analisis de la propagacion geográfica de la información en Twitter revela que los usuarios suelen enviar tweets desde una única localización geográfica. Además, el nivel de geolocalización asociada a las relaciones sociales varía entre países y encontramos algunos paises, como Brasil, donde es más que la información se mantenga local que en otros como Australia. (iv) Nuestro análisis de la carga de Twitter indica que el proceso de llegada de tweets sigue un modelo gausiano con un marcado patrón día-noche. En definitiva, el trabajo presentado en este tesis permite aumentar nuestro conocimiento sobre el ecosistema de las redes sociales en direcciones esenciales como pueden ser la formación y crecimiento de redes sociales o la propagación de información en estos sistemas. Los resultados reportados ayudarán a desarrollar nuevos servicios sobre las redes sociales.Programa en Ingeniería TelemáticaPresidente: Antonio Fernández Anta; Vocal: Marco Mellia; Secretario: Francisco Valera Pinto

Resource Efficient Urban Delay/disruptive Tolerant Networks

Ph.DDOCTOR OF PHILOSOPH